Manufacture of bags



Nov. 24, 1959 w. E. sTAGEBERG MANUFACTURE 0F BAGS original Filed Nov. 2e, 1954 2 Sheets-Sheet 1 T LMWWARHWI r Nov. 24, 1959 w. E. smal-:BERG 2,913,966

v MANUFACTURE oF BAGS Original Filed Nov. 26, 1954 2 Sheets-Sheet 2 United States Patent O MANUFACTURE F BAGS Wilfred E. Stageberg, Minneapolis, Minn., assignor t0 Bemis Bro. Bag Company, St. Louis, Mo'., a corporation of Missouri Original application November 26, 11954, Serial No. 471,462. Divided and this application September 30, '1955, Serial No. 537,632

8 Claims. (Cl. 93-20) V26, 1954, now abandoned.

Heretofore,'bags ofthe class described have been made from gusseted tubing formed with a heat-sealed seam between overlapping margins of the sheet material with the seam disposed generally centrally of one wall o-f the tubing. This makes it impracticable to have any printing on the seamed Wall of the tubing, and also results in the undesirable presence of a loose ap of the sheet material extending throughout the length of the seamed wall of the tubing. Among the several objects of this invention may be noted the provision of a method and apparatus for forming a continuous web of heat-scalable sheet plastic material, such as polyethylene, into continuous gusseted tubing with a longitudinal tube seam along one edge of the tubing, rather than generally centrally of one wall of the tubing, thereby making it practical to have printing on both walls of the tubing and eliminating the stated undesirable flap; the provision of a method and apparatus of the class described which enables the continuous `production of gusseted tubing of the type specilied; and the provision of a method and apparatus of the class described enabling the economical production of tubing of the type specied. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions and methods hereinafter described, the scope of the invention being indicated in the following claims.

A In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 is a plan view of an apparatus of this invention;

Fig. 2 is a vertical longitudinal cross section of the apparatus, taken on line 2 2 of Fig. l;

Figs. 3-8 are enlarged vertical transverse cross sections, partly broken away, taken on lines 3-3 to 8--8, respectively, of Fig. l; and

Fig. 9 is a perspective illustrating the tubing produced by the method and apparatus `of this invention, and showing `how the tubing may be formed into bags.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings, Figs. 1-8 illustrate the formation in accordance with this invention of a continuous web 1 of heat-scalable sheet material, such as polyethylene, into the gusseted bag tubing indicated at 3 in Fig. 9, L

the tubing having a heat-sealed longitudinal seam 5 at one edge. Referring more particularly to Figs. l and 2, the formation of the web into the tubing is shown to be carried out in a tuber of this invention `design'atedin its entirety by reference character 7. The tuber comprises Patented Nov. 24, 1959 rice a pair of side frames 9 and 11. Extending between the side frames at the forward end of the tuber (its right end as viewed in Figs. 1 and 2) are draw rolls 13 and `15. These are adapted to draw the web' 1 from a supply roll 17 of the web material and to feed the'web continuously through the tuber. The supply roll 17 is mounted in vertical position adjacent the rearward end of the tuber. As the web is continuously fed forward through the tuber, Ia series of operations is performed on the web by means `to be described to form it into the tubing 3, the finished tubing 3 entering the draw rolls and being fed forward -thereby for subsequent operations. 1

The iirst operation on the web 1 as it unwinds from the supply roll 17 is the folding of the web on-lines extending longitudinally of the web and located intermedi- -ate the side edges 19 and 21 of the web to form it into a doubled web having walls 23 and 25 joined by a gusset 27 along one side of the doubled web. The web is shown in its flat condition as it unwinds fromthe supply roll 17 at the left end of Fig. 2. Fig. 3 shows the web in transition to the doubled web condition prior to the completion of the formation of the gusset 27, and Fig. 4 shows the doubled web with the gusset 27 completely formed. In the transition, the web, which unwinds from the supply roll in a vertical plane, is so folded that the doubled web is horizontal, with wall 23 of the doubled web constituting the upper wall and wall 25 the lower wall. l

The lines on which the web is folded to form the doubled web are designated 29, 31 and 33 (see Figs. 4-9). These lines are so located that the width of the wall 25 is slightly greater than the desired nal width for the tubing 3 and the width of the wall 23 is greater than the width of the wall 25 by a distance sufficient vto provide a second gusset at the other side of the doubled web from the gusset 27. This distance yis preferably slightly greater than twice the desired gusset width. This allows for some trimming off during a subsequent heat-sealing operation to be described.

The second operation on the web involves the disposition of a portion ofthe wall 23 of the doubled web to draw the edge 19 of the wall 23 into line or at least substantially into line with the'edge 21 of the wall 25 with the side margins of the walls adjacent these edges in face-to-face contact. As shown best in Figs. 4-6, this is accomplished by forming a portion of wall 23 into a pleat generally designated 35, this pleat being folded inward and overlying the `wall 23. The pleat 35 is formed by folding a portion 37 of the wall 23 inward on a longitudinal line 39 to overlie the wall 23, and folding a portion 41 of the wall 23 between portion 37 and the edge 19 of wall 23 outward on a longitudinal line 43 to Voverlie the portion 37 and to extend outward beyond portion 37 to the edge 21 of wall 25. Line 39 is located inward from the edge 21 of wall 25 a distance corresponding to the desired gusset panel width, and is spaced from the edge 19 of wall 23 (considering wall 23 as if it were flat) a distance corresponding to three times the desired gusset panel width, taking into account the slight excess of material allowed for trimming. Line 43 is spaced from the edge 19 of wall 23 (and from theedge 21 of wall 25) a distance corresponding to twice the desired gusset panel width, again taking into account the slight excess of material allowed for trimming. The pleat 35 is constituted by portion 37 and the overlying part of portion 41.

The third operation on the web is the heat-sealing of the side margins of the walls 23 and 25 adjacent their in the-side margins are accessible -for applicationof heat and pressure from above and below, the pleat 35 being folded inward so as not to overlie the side margins.

Finally, tthe pleat 35 is folded outwardon line 39 to overlie the marginalfportions o'f walls 2'3 'and'25 which lie outward of the line v39. In this operation the portion 41-of the wall`23 (which has a width corresponding Vto twice 'the desired gusset panel width) is folded inhalf on'a line'45 coincident with line 39 to form the second gusset, -this vsecond gusset being designated by `the referrence character41 since iit is `constituted by the folded portion 41. The transitionof'the-pleat`35 from itsinwardly folded to its outwardly folded -position to form the second gusset 41'is illustrated in Figs. 6-8.

Por carrying out the operation of doubling the `web l and forming the first gusset 27, the tuber 7 comprises `vertically larranged upper andlower'triangular horns 47 and -'49 with a space 51 between Vthe horns. The Vside frame lll has a rearward extension 53 beyond .the rearward end of lside frame 9,-and theh'orns aremounted on this "extension, The kupper vhorn has 'an upper 'triangular face 55'inclined downward inforward direction. The lower'horn has a lower triangular face y57 inclined upward in'forward direction. The 'web 1 unwinding from the supply roll 17 travels around "a vertical guide roll 58 at the rearward end of frame extension 53, and thence Aover :the horns. The horns initiate .the 'doubling of :the web.

"The upper -wall of the lpartially doubled web :leaving the horns is gidedunderanupper,horizontal guideroll 59 and thence over an upper inside former blade 61, and th'e lower `wall of the partially doubled'web is guided over a lower guide'roll 63 and thence under 'a 'lower in- -/s'ide formenbla'der 65. Rolls 59 and 63 are located in a vertical .plane at the rearward end Vof side 'frame 9. Blades 61 and l65 are mountedon side frame 11, extend- .ingas cantilevers toward side frame 9. Blade 61 is inclined downward and blade65 isi'nclined'upward in forward direction, converging toward their forward ends so 'ithat :the doubled web is flattened. The gusset 27 is formed by '-upper `and lower intucking blades 67 and 69 mounted on side frame 9 and extending as cantilevers toward side'frame :11. Blade 67` extends under the upper 'inside former blade 61 and is inclined downward like -blade 61. Blade'69'extends over the lower inside former Iblade '65 `and is inclined upwardlike blade 65. The planes of Ablades 67'and 69 converge in forward direction. Each fofblades y67 and 69 vhas an inside intucking edge 'which `zis'angled toward '.the'sideframe 11 in forward direction. lThe 'intucking 'edge of blade 67 is designated 71, and the `intucking/.edge of blade 69`is designated 73 (see Fig. 3). The overlap `of blades 61, .67 and 65, .69 at their forward ends corresponds to the desired gusset width.

',The formation lof the pleat 35 is carried'out'by'means #of upper and loweripleating blades 75 and 77 forward of :thelinsideformerblades and the intucking blades. The upper pleating `blade 75 is mounted on'side frame 11 and fextends'as `a'cantilever toward side lframe 9. .Its plane is vslightlyinclined upward Vin forward direction (see Fig. 2). It rhas an inner edge 79 which angles toward the fsideframe'9 in forward direction. The lower pleating blade is rmounted von the side frame 9 and extends as a Acantilever toward the side frame 11. Its plane is inclined upward in forwardldirection at a greater angle than blade -75. The planes of blades 75 and 77 converge inforward direction. Blade 77 has an inner end edge 81 4whichis:generallyparallel to theside frames. .The folding on line.39 occurslon this edge 81.

A right side portion of the upper wall 23 ofthe .doubled web formed by the horns and the 'former blades and intucking blades is folded up against the free .en`cl'83-of acantilever guide roll 85 projecting from side "frame 49 'toward A'side frame 11 and outward yaround the l"inner `edge 'of the upper Apleating yblade 75 to inititate the 'formation l'of `the pleat35. -Roll `I85 is 'locatedbe- 4tween the .forward end of the former .blades and the rearward end of the pleating blades. The doubled web having the gusset 27 issuing from the former blade travels under the roll 85, which completes the flattening of the doubled web. The yconvergence of the planes of the pleating blades and the divergence of the inner edges 79 and 81 ofthe pleating :blades .in forward direction form the pleat 35 with the pleat folded inward as shown in Figs. 5 and-6.

The doubled and pleated web issuing .from the pleating blades travels over a guide roll 87 (which completes the llattening of the pleat), under a lower guide roll 89,

thence up and forward around 'a roll 91. As the web travels over the roll 91, the Sidemargins of'the walls 23 and 25 are heatfsealed'adjacent ytheir edges 19 and 21 to form the seam 5 by means of a pair of heated sealing rolls 93 and 95. Roll 93 is shown as coaxial with roll '91 (see Fig. 6') and roll 95 `is mounted on a shaft 97 extending from the side frame 1l. It will be understood that the sealing rolls may be heated as by means of electrical resistance heating 4elements incorporated therein. The sealing rolls are preferably such as to form a line seam and to trim off excess material outward'of the seam.

As the web travels `from the rolls 93, 95 to the draw rolls 13 and 15, the pleat 35 is folded over from its inward position to form the gusset'41. 'This is accomplished by guiding the 'pleat *between the adjacent ends of two coaxial cantilever rolls 99 and 101 .(see Figs. 1 and v7) to turn the pleat from its'Fig. y6 position to the vertical position shown in Fig. 7, then over a table 103, along 'a folding blade 4105 and under la spring presser foot 107.

This completes the formation of the tubing 3 with the 4heatLseale'd seam 5 along the fold of galsset 41 at the juncture of wall'25and the gusset/41.

Fig. 9 shows the tubing 3 being segmented to form bags such as the bag indicated at 109 by transversely severing the tubing on lines indicated at 111 and heat sealing the resultant bag lengths on transverse lines indicated at -113 to form bottom closures for the bag lengths.

r In view of the above, it'will 'be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions and methods without departing yfrom the scope of the invention, it is intended that all matter contained in the above description orsh'own vin the accompanying drawings shall beinterpreted as illustrative and not vin a limiting sense.

I claim:

1. The method of forming 'gussete'd tubing from 'a web of heat-scalable sheet material, comprising continuously feeding the web,"foldingthe `web on lines extending longitudinally ofthe web land located intermediate the side edges of the web to form it into 'a doubled web having walls joined by a gusset along vone side of lthe doubled web, said lines being so located that one wall is wider than the other in 'amount sufiicient to provie a second gusset, folding said wider wall to draw its edge back from the edge of the other wall and to bring said edges substantially into alignment with the side margins of the walls in face-to-face contact and also to form gussetforming portions one of lwhich includes said side margins and the other of which is folded away from said side edges on the outside of the wider wall to lie away from said side margins so that they are clear for heat sealing, heat sealing said side margins, and then folding said other gusset-forming portion outward to form the second gusset along the other side of the doubled and heat-sealed web.

2. The method of forminggusseted tubing from a web of heat-sealable sheet material, comprising continuously feeding the web, folding the web on lines extending longitudinally `of 'the 'web and located intermediate vthe 'side 'edges 'of the vvweb to 'form l:it -into Ia -doub`led web having walls joined by a gusset along one side of the doubled web, said lines being so located that one wall is wider than the other in amount sufficient to provide a second gusset, forming a pleat in the wider wall to draw its edge back from the edge of the other wall and to bring said edges substantially into alignment with the side margins of the walls in face-to-face contact, the pleat being folded away from said side edges and lying flat on the outside of said wider wall to lie away from said side margins so that they are clear for heat sealing, heat sealing said side margins, and then folding the pleat outward to form the second gusset along the other side of the doubled and heat-sealed web.

3. The method of forming gusseted tubing from a web of heat-scalable sheet material, comprising continuously lfeeding the web, folding the web on lines extending longitudinally of the web and located intermediate the side edges of the web to form it into a doubled web having walls joined by a gusset along one side of the doubled web, said lines being so located that one wall i-s wider than the other a distance corresponding to twice the gusset panel width, forming a pleat in the wider wall to draw its edge back from the edge of the other wall and to bring said edges substantially into alignment with the side margins of the walls in face-to-face Contact, said pleat being formed by folding the wider wall inward on a line spaced from the edge of said wider wall a distance corresponding to three times the gusset panel width and folding the wider wall outward on a line spaced from the edge of said wider wall a distance corresponding to twice the gusset panel width, the pleat thereby lying at on the outside of the wider wall away from said side margins so that they are clear for heat sealing, heat sealing said side margins, and then folding the pleat outward to form a second gusset along the other side of the doubled and heat-sealed web.

4. A tuber having former and intucking blades for forming a web of heat-sealable sheet material into a doubled web having walls joined by a gusset along one side of the doubled web with one of said walls wider than the other in amount suiicient to form a second gusset along the other side of the doubled web, means for folding the wider wall to draw its edge back from the edge of the other wall and to bring said edges substantially into alignment with the side margins of the walls in faceto-face contact and also to form gusset-forming portions one of which includes said side margins and the other of which is folded away from said side edges on the outside of the wider wall to lie away from said side margins so that they are clear for heat sealing, means for heat-sealing the walls along said edges, and means for folding said other gusset-forming portion outward to form the second gusset along the other side of the doubled and heat-sealed web.

5. A tuber having former and intucking blades for forming a web of heat-sealable sheet material into a doubled web having walls joined by a gusset along one side of the doubled web with one of said walls wider than the other in amount sufficient to form a second gusset along the other side of the doubled web, means for forming a pleat in the wider wall to bring its edge substantially into line with the edge of the other wall and to bring the side margins of the walls into fact-to-face contact, said means forming the pleat to lie away from said side margins, means for heat-sealing the walls along said edges, and means for folding over the pleat to form the second gusset along the other side of the doubled and heat-sealed web.

6. A tuber having former and intucking blades for forming a web of heat-scalable sheet material into a doubled web having walls joined by a gusset along one side of the doubled web with one of said walls wider than the other in amount sufficient to form a second gusset along the other side of the doubled web, a pair of blades for forming a pleat in the wider wall to bring its edge substantially into line with the edge of the other wall and to bring the side margins of the walls into faceto-face contact, said blades being arranged to form the pleat in an inwardly folded position adjacent said edges, means for heat-sealing the Walls along said edges, and means for folding over the pleat to an outwardly folded position thereby to form the second gusset along the other side of the doubled and heat-sealed web.

7. A tuber comprising a pair of side frames, means for forming a web of heat-sealable sheet material into a doubled web having walls joined by a gusset along one side of the doubled web with one of said walls Wider than the other in amount sufficient to form a second gusset along the other side of the `doubled web, said means comprising a pair of horns for initiating doubling of the web, a pair of inside former blades extending from one side lframe toward the other and a pair of intucking blades extending from said other toward said one side frame, means for forming a pleat in the wider wall to bring its edge substantially into line with the edge of the other wall and to bring the side margins of the Walls into face-to-face contact comprising a pleating blade extending from one side frame toward the other and a pleating blade extending from said other ltoward said one side frame, said blades forming the pleat in an inwardly folded position adjacent said edges, a pair of heat-sealing rolls for heat sealing the walls along said edges, and means for folding over the pleat to an outwardly folded position thereby to form the second gusset along the other side of the doubled and heat-sealed web.

v8. The method of forming a gusset at one margin of first and second superposed continuous layers of flexible heat-scalable sheet material, the first layer extending laterally beyond an edge of the second, comprising continuously feeding said layers in longitudinal direction, folding the first layer to draw the edge thereof which was originally located outward of said edge ofthe second layer back from the edge of the second layer and to bring said edges substantially into alignment with the side margins of the layers in face-to-face contact and also to form gusset-forming portions one of which includes said side margins and the other of which is folded away from said side edges on the outside of said first layer to lie away from said side margins so that they are clear for heat sealing, heat sealing said side margins, and then folding said other gusset-forming portion outward to form a gusset.

References Cited in the iile of this patent UNITED STATES PATENTS 

